This application describes development of a broad-spectrum vaccine targeting multidrug resistant (MDR) organisms, principally related to healthcare-associated infections (HAIs). Our premise is that an effective way to prevent antimicrobial resistance is through vaccines rather than continued introduction of new drugs. Our development program is based on two cell wall antigens of the fungus Candida albicans: Als3p, a multi- function adhesin/invasin; and Hyr1p, which enables C. albicans to evade phagocyte killing. Vaccination of mice with either antigen provides significant protection against disseminated infections caused by Candida species and vulvovaginal candidiasis (VVC) due to C. albicans. Importantly, vaccination with both antigens synergistically protect mice from VVC. Using innovative computational molecular modeling and bioinformatic strategies, we identified highly significant three dimensional (3-D) structural and functional homology between Als3p, and methicillin resistant Staphylococcus aureus (MRSA) surface adhesive molecules, including clumping factor A. Similarly, Hyr1p, shares 3-D structural homology to MRSA SraP, an adhesin to platelets. Hyr1p also shares striking structural homology with hemagglutinin/hemolysin of MDR Acinetobacter baumannii (AB) and carbapenemase-producing Klebsiella pneumoniae (CPKP). Active immunization with the recombinant N terminus of Als3p (rAls3p-N) results in >50% survival in an otherwise fatal murine model of staphylococcemia and protects mice from Skin and Skin Structure Infection due to MRSA. Similarly, active or passive immunization (with a monoclonal antibody) targeting the recombinant N-terminus of Hyr1p protects mice from MDR AB, and CPKP infections. Thus, our vision is to develop a ?cross-kingdom? dual antigen vaccine targeting Candida, MRSA, and MDR AB and CPKP. All are important leading cause of HAIs. Specific aims are: a) optimization of the dual rAlsp3-N/rHyr1p-N vaccine by synergy evaluation, fine- tuning of antigen dose, and use of clinically-safe newer adjuvants; b) conduct GLP-enabling studies including analytical assay development/optimization, formulation scale up of an optimized dual antigen vaccine and stability studies; and c) evaluate the final vaccine formulation for activity with and without antibiotics and perform an IND-enabling GLP-toxicity study of the optimized final vaccine formulation. In collaboration with NovaDigm Therapeutics, we advanced the development of rAls3p-N formulated with aluminum hydroxide (i.e. NDV-3A) from the academic laboratory to a phase 1b/2a trial showing efficacy of the vaccine in protecting women <40 years old from recurrent VVC. Thus, this proposal will leverage our combined strengths in basic discovery and product development of convergent vaccine antigens protecting against diverse human pathogens.